Monitoring and control of hearth refractory wear to improve blast furnace operation

Abstract

Refractory wear and skull growth on the hearth walls and the bottom of the blast furnace have been researched. A series of thermocouples were installed in the hearth, and the temperature measurements were recorded in a structured query language every minute. A heat transfer model was used to study the temperature evolution and hearth wear profile using a commercial software package (MATLAB version 5.0) based on computational fluid dynamics. The location of the 1150°C isotherm in the hearth lining has been calculated. An online monitoring tool was used to analyse the temperature distribution in the hearth and offers, to the plant operators, periodic information on the refractory state. Electromotive force (EMF) probes were installed in the hearth to estimate the variations in the liquid level in the hearth and to determine the thermal state (TS) evolution. Good correlation is seen between EMF and TS, and the EMF amplitudes in the different tapholes follow and even precede the local TS.     

Blast furnace campaign extension by fundamental understanding of hearth processes

In blast furnace ironmaking hearth performance has a critical effect on the efficiency of the operations and the campaign duration. In this paper the relationship between hearth lining design and lining wear is analysed, based on plant data and research activities of Tata Steel Europe that is supported by information published elsewhere. Tools to model, monitor and visualise the hearth processes are discussed. Current hearth management practices are illustrated. It is noted that the varying process conditions make current campaigns less predictable than previous ones. The hearth lining design rules developed decades ago seem to be in need of revision.     

Improvement in casting practice by controlling the drainage rate and hearth liquid level to develop an efficient casthouse management practice in blast furnace

The key to excellent casthouse operation are low cost, high productivity, dry hearth and high casting rate while minimising the consumable material. The stable blast furnace operation requires proper control of drainage rate of liquid hot metal and slag from hearth. The productivity of blast furnace can be effectively increased if drainage rate is considerably increased. If the drainage rate is controlled, the periodic tapping of hot metal and slag from hearth can be made effective. This paper highlight the improvement made in casting practice by controlling the hearth liquid level in blast furnace. The improvements have made significant change in casthouse management. It is well demonstrated that various casthouse operations have migrated from one regime of operation to another regime and various consumable items are significantly reduced. The importance of increasing the drainage rate in improving the productivity of blast furnace is explained in details.     

高炉料仓料位在线检测及其变化趋势分析

设计了高炉料仓料位在线检测方案,介绍了调频连续波雷达的测距原理,利用傅立叶变换从雷达回波信号的频率和相位中提取距离信息,并应用于攀钢2号高炉料仓料位检测中.结果表明,调频连续波雷达能够准确测量料仓料位高度.     

Corrosion mechanism research and microstructure analysis of Baosteel No. 3 blast furnace hearth

Baosteel No. 3 blast furnace hearth was divided into tuyere area, taphole area, taphole upper side wall and taphole lower side wall according to different working situations. Through chemical composition analysis, scanning electron microscopy, X-ray diffraction, energy dispersive spectrometry and other means, chemical composition and microstructure of different parts of hearth carbon brick were analyzed and markedly different corrosion mechanisms of these areas were found. Zn element in form of ZnO mainly deposited on the hot side of carbon brick. There was no obvious evidence that Zn permeates into carbon bricks and erodes them. Except for taphole area, K, Na, and Fe contents from hot side to cold side gradually rise and fall, resulting in the decrease of apparent porosity, the increase of density and the higher thermal conductivity compared with those of new carbon brick. The higher content of Fe in carbon brick leads to more serious erosion because Fe has greatly changed the physical properties of carbon brick. In the taphole area, the contents of Si and Al present obvious concentration gradient because of the mechanical souring of molten iron and slag. The SiO₂ and Al₂O₃ particles that have different expansion factors with carbon brick damaged the carbon substrate because of temperature fluctuation. The graphitized carbon found on H4 where is the most serious corrosion site means that the carbon brick ever directly contacts with molten iron.     

Analysis on the stamping coke dissolution of hot metal in the blast furnace hearth

By utilising the carburiser-cover methods, this article mainly focuses on the impacts of different carbon sources on hot metal carburising in the blast furnace hearth. The carburising rate, an indicator of the evaluation of coke including stamping coke and graphite, is compared at 1450–1550°C. Additionally, the apparent activation energy of carburisation of coke 1, coke 2 and graphite are 236.9, 178.8 and 46.0?kJ?mol^?1, respectively. The difference in activation energy for the three carbon sources in question is attributed to the mineral matters in coke, because it is capable of influencing the effective contact interface area between the liquid iron and carbon. As to the overall viscosity of the interface layer between the hot metal and carbon, it is mainly affected by the temperature and ash content and its composition. When the temperature increases from 1450 to 1550°C, the viscosity of the minerals on the interface layer will decrease correspondingly. The defined surface area of mineral reduces from 86.7 to 70.7% in coke 1 and from 82.5 to 69.3% in coke 2. Finally, to improve the carburising rate the basicity of the oxide contents in the coke should be increased by adding CaO or MgO.     

高炉开铁口机的合理结构

开铁口机是高炉炉前的主要设备之一。目前我国高炉设备中唯一没有实现国产化更新换代的就是开铁口机。本文阐述了我国从日本、德国、前苏联和英国引进５种不同结构类型开铁口机的性能和特点，并结合这些性能和特点研制出适合我国现有３００ｍ３～２５００ｍ３高炉的电振打开铁口机。     

高炉炉缸破损的原因与控制

 近年来,中国高炉长寿技术取得了长足的进步,部分高炉寿命达到国际先进水平,但同时也出现数十座高炉发生炉缸事故或异常侵蚀破损。高炉长寿技术是一项综合技术,高炉要实现长寿除需要保障炉衬、炉体材质和建筑施工质量外,科学合理的设计是关键,高炉生产操作监控维护是基础。基于对多座高炉长寿技术应用状况和高炉炉缸的破损调查,从设计、操作等多方面对炉缸破损原因进行分析,并提出了长寿炉缸设计的优化原则和实现炉缸长寿的生产操作、监测、维护及管理的控制对策。     

Blast furnace circumferential process symmetry: effect of flow distribution in hot blast systems

Abstract

Solid particle flow patterns in the moving bed zone of a melter/gasifier were studied using discrete element method (DEM). Interparticle forces were calculated using the Hertz–Mindlin no slip contact model. The simulation results of the solid particle flow patterns agree well with the experimental results exhibited by tracer particles. The solid particle flow pattern and descending velocity were studied, as well as the effect of the discharge rate of solid particles in the raceway on solid particle flow pattern in the moving bed.

Results show that the moving bed could be divided into four subdomains based on the velocity of solid particles. A stagnation zone with semielliptic geometry is formed at the central bottom of the moving bed during drainage of solid particles. Furthermore, the simulated results of compressive force among solid particles in the moving bed zone indicate that the deadman zone undergoes a high degree of compressive force, especially at the centre of the gasifier. This finding implies that more compressive force resistant solid material should be placed at the centre zone by manipulating solid particles fed into the melter/gasifier.     

关于高炉炉缸长寿的关键问题解析

 高炉长寿化是大型高炉发展的必然趋势,实现高炉长寿的关键在于弄清高炉侵蚀的根本原因。从高炉炉缸侵蚀机理、高炉炉缸象脚型侵蚀原因、高炉炉缸圆周方向侵蚀不均匀性、高炉冷却强度与冷却效率以及高炉炉缸维护技术等5个方面探讨了高炉长寿存在的共性问题,指出高炉炉缸炭砖损毁的本质是碳不饱和铁水对炭砖的溶蚀。具体结果表明,首先,高炉炉缸象脚型侵蚀最严重部位位于高炉炉缸死料柱的根部位置;其次,阐明了直接导致高炉存在不均匀侵蚀的主要原因在于冷却系统的冷却水量和送风系统的风量在高炉周向方向分配不均匀;然后,阐明了冷却系统的作用本质是降低耐火材料热面温度,并提出了高炉冷却强度指数及高炉冷却效率指数;最后,分析了采用无钛矿护炉和钛矿护炉两种模式的高炉炉缸维护技术。     

Fuzzy grey relational analysis for influencing factors of heat transfer in a blast furnace hearth

For a blast furnace, the hearth erosion profile is mainly determined by the temperature distribution in the refractory. Numerical simulation was conducted to simulate the heat transfer and flow in a blast furnace hearth. Based on the simulation results, a fuzzy grey relation analysis method combining the grey entropy analysis and Euclidean grey relation analysis was put forward for evaluating the effects of various factors on the temperature distribution of sample areas at the bottom and sidewall refractory. Impacts of four typical factors (porosity of deadzone, floating height of deadman, radius of deadzone and temperature of cooling water) were evaluated by grey entropy analysis and Euclidean grey relational analysis, respectively. Lastly, a fuzzy grey relational analysis was employed to make a comprehensive evaluation of the four factors. Results have shown that the floating height of deadman is the dominant factor affecting the temperature distribution both on the bottom and sidewall.     

Influences of taphole numbers on hot metal circumferential flow in blast furnace hearth

The circumferential flow of hot metal has a significant influence on the hearth erosion. Because the situation of the hearth is ??black box??, there is no direct examine method for the hot metal flow. Based on the computational fluid dynamics, the streamline and velocity were studied with different deadman conditions and different tapholes. The results show that when the hot metal tap with single or double tapholes (with the angle of 40??) and the deadman is at the sitting condition whose center is fine coke, the circulating hot metal is the most serious in the hearth. When the hot metal tap with double tapholes(with the obtuse angle), the circumferential flow of hot metal is weakened. The sitting deadman could strengthen the hot metal circulution. However, the floating deadman could weaken hot metal circulution, but it strengthens the hot metal flow of the bottom.     

高炉合理鼓风动能与炉缸活性的关系

 通过分析高炉鼓风动能与炉缸活性的关系,认为合理的鼓风动能不仅是保持炉缸活性良好的前提条件,更是高炉操作者调节炉况的重要手段之一。通过研究合理鼓风动能的理论依据和计算方法,发现高炉合理鼓风动能不仅需要随着高炉容积的增大而增大,而且需要有合理的风量和风口面积。通过比较不同容积高炉所对应的风量,提出了风量比和风量系数的概念;介绍了本钢新1号高炉通过调节风口面积探索合理鼓风动能的过程。对高炉在不同鼓风动能条件下所产生的各种直观现象和仪表变化进行了说明,针对这些现象就可以判断出鼓风动能是否在合理范围内,并进行相应的调节。因此,合理的鼓风动能需要适应高炉生产的各方面条件的变化,这就需要对合理鼓风动能进行不断的探索和实践,以形成应变的合理的送风制度,确保高炉生产长期稳定顺行。     

新型长寿命风口的研制

本文介绍了高炉风口的使用情况及对提高风口寿命的研究，较详细地介绍了新型风口研制过程，并介绍了风口的修复方法。     

高炉风口换热过程数值模拟

高炉风口是高炉输送高温鼓风和煤粉必需的冷却设备。以外观尺寸相同的空腔式风口和贯流式风口为研究对象,运用数值模拟分析软件Fluent,采用k-epsilon双方程模型,压力基求解方法,对两者的换热过程进行模拟并对照分析了入口流速对其换热性能的影响。结果表明:随着水流量增加,风口表面温度下降,但进出口压损增加;相同水流量情况下,贯流式风口比空腔式风口换热能力更强,但产生的压损更大。综合考虑,2种模型的进水流速均以5～10m/s为宜。     

高炉炉缸长寿智能管理系统的开发与应用

针对当前高炉长寿管理滞后和针对性差的现状,将高炉炉缸工艺设计、传热学理论与高炉操作工艺相结合,开发了一套炉缸长寿智能管理系统。除传统炉缸侵蚀模型的炭砖侵蚀曲线计算功能以外,还具有凝铁层在线监控、炉缸气隙判断、凝铁层减薄原因诊断和给出针对性改善建议4项核心功能。该系统全部模块均进行在线监测、计算、诊断和建议,其关键目的不是计算侵蚀曲线,而是防止炉缸侵蚀的发生,可为做好高炉的长寿管理、延长高炉寿命起到重要作用。     

2500m~3高炉炉缸炉底侵蚀监测模型的开发与应用

高炉炉缸炉底是影响高炉寿命的限制性环节之一。为了避免发生严重侵蚀甚至烧穿等重大事故,针对马钢2 500 m~3高炉,开发了利用热电偶或者冷却设备数据监测炉缸炉底侵蚀监测模型。采用该模型,监测了马钢2 500 m~3高炉的炭砖残存厚度变化。该模型可用于判断炉缸炉底是处于侵蚀阶段还是处于堆积阶段,对高炉操作者分析、判断和调节炉况有指导作用。     

Revamping of CSN BF2 hot blast stove no. 1

Abstract

CSN BF no. 2 has only three hot blast stoves. Owing to the operational risks as well as output losses associated with the BF operation with just two hot blast stoves, the revamping time of this equipment becomes a crucial issue, requiring special attention in each phase of the project from planning to execution so as to shorten the time as much as possible. According to this context, the present paper describes in detail the main technologies used in the last revamping of hot blast stoves carried out in February 2007. These technologies included an accelerated cooling down curve, air conditioning system (good working condition) and convection heating system, which in association with an innovative construction methodology, involving movable and multilevel platforms, has allowed the project to be completed from blow to blow in a record time of just 67 days and 10 h, resulting in a reduction of costs around R$3·4m.     

高炉炉缸破损调研分析

高炉炉缸安全是高炉长寿的主要限制环节,首钢股份公司环保限产期间对2号高炉进行了在不切割炉壳情况下的炉缸保护性清理和浇注修复施工。在此期间对高炉炉缸的破损情况进行了调研,研究了首钢股份公司 2 号高炉风口以下炉缸渣皮、风口区域、出铁口前泥包的状态和炉底陶瓷垫的侵蚀状况,并分析了造成炉缸炭砖侵蚀的原因及炉缸中钛和锌元素的物相。研究发现炉底陶瓷垫未形成锅底状侵蚀,越是靠近炉墙位置,陶瓷垫侵蚀越严重,说明了炉缸活跃度不够。而象脚区炭砖侵蚀主要是受铁、钾和硫等元素的渗透侵蚀;炉底象脚区域发现大量古铜色碳氮化钛沉积物,沉积物呈带状分布;破损炉缸中发现的大量ZnO富集物是黄绿色而非传统的白色。此次破损调研为后期炉缸浇注、高炉操作以及今后的炉缸设计提供现实可靠的依据,其意义重大。     

高炉炉缸死焦堆受力分析与计算

建立了一个特殊情况下死焦堆在炉缸中的受力模型,推导出了最小死铁层深度的计算公式,并用某高炉解剖数据进行了验证,结果表明该模型可靠.在此基础上提出了一般条件下的死料柱受力模型,推出了一个用于估算一般情况下死焦堆浮起高度的公式,并讨论了死焦堆浮起高度与炉渣液面高度的关系.